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Hypertension (High Blood Pressure)

Last Updated: Mar 1, 2019


Hypertension, also called high blood pressure, is a condition in which the force of the blood against artery walls is elevated. Approximately one out of three adults in the United States has hypertension. This condition is a major cause of cardiovascular disease and often causes heart attacks, strokes, and kidney failure.

Systolic and diastolic are the terms used to describe the two values measured during a blood pressure reading. The systolic pressure is the force inside the arteries when the heart beats (pumps blood out to the arteries). The diastolic blood pressure is measured between beats, when the heart is at rest. Blood pressure readings are recorded with the systolic number written above the diastolic number, for example 110/70 mmHg. In medicine, the standard unit for measuring pressure is a millimeter of mercury (mmHg).

Classification of Blood Pressure Levels in Adults, in mmHg

  • Normal: systolic is less than 120 and diastolic is less than 80
  • At risk (pre-hypertension): systolic is 120-139 or diastolic is 80-89
  • Hypertension Stage 1: systolic is 140-159 or diastolic is 90-99
  • Hypertension Stage 2: systolic is greater than or equal to 160 or diastolic is greater than or equal to 100

Causes and Risk Factors

Heart cross-section

Frequently, the cause of hypertension is unknown; this form of hypertension is called essential hypertension or primary hypertension. When hypertension is caused by another medical condition - for example, kidney disease or thyroid disease - the term secondary hypertension is used. Additionally, some medications such as birth control pills, steroids, and over-the-counter cold medications elevate blood pressure.

Risk Factors For Hypertension

  • Family history of hypertension
  • African-American ethnicity
  • Obesity
  • Age
  • Birth control pills
  • Sedentary lifestyle
  • Alcohol abuse
  • High-fat diet
  • High salt (sodium) diet
  • Low potassium diet
  • Smoking

Children and adolescents normally have lower blood pressures than adults, and the incidence of hypertension increases with age. Unfortunately, the incidence of pre-hypertension and hypertension is steadily increasing in children and teens because of the growing problem of childhood obesity.

Symptoms and Complications

Typically, people with hypertension do not experience any symptoms; therefore, many patients are unaware that they have a problem until complications arise. The only way to know whether hypertension is present is to measure it with a blood pressure gauge.

Untreated hypertension often leads to serious complications. High blood pressure damages arterial walls and promotes plaque accumulation, resulting in narrowing (stenosis) and hardening of the arteries throughout the body. Narrowing of the arteries leads to inadequate blood flow and damages organs.

Hypertension leads to the following complications:

  • Coronary artery disease that causes inadequate blood flow and injury to the heart (heart attack)
  • Weakening of the heart so that it fails to pump enough blood to the body (heart failure)
  • Inadequate blood flow to the brain (stroke)
  • Kidney failure
  • Inadequate blood flow to the legs (peripheral vascular disease)

Diagnosis and Treatment

A person’s blood pressure normally varies throughout the day and is usually lower during sleep and higher during periods of stress or activity. Because of this variability, blood pressure readings at two separate office visits help determine whether a patient’s usual blood pressures are high.

Usually, the goal of treatment is to reduce blood pressure to below 140/90. Because of the increased risk of complications in adults with coronary artery disease, diabetes, or chronic kidney disease, the treatment goal in these groups is a blood pressure below 130/80.

Hypertension is initially treated with lifestyle changes. However, in most cases, physicians recommend a combination of lifestyle changes and antihypertensive medications to control blood pressure.

Lifestyle Changes

  • Dietary approaches to stop hypertension (DASH) emphasize vegetables, fruit, whole grains, low-fat and low-sodium foods
  • Exercise
  • Healthy body weight
  • Quitting smoking
  • Stress management and relaxation techniques

Antihypertensive Medications

Physicians may prescribe one or more medications based on a patient’s response to treatment, other medical problems, and tolerance of side effects.

  • Diuretics, also known as water pills, simulate the kidneys to remove water and salt.
  • Angiotensin-converting enzyme (ACE) inhibitors block the body’s production of angiotensin II (a hormone that constricts blood vessels and causes hypertension). A dry cough is the most common side effect.
  • Angiotensin II receptor blockers (ARBs) prevent angiotensin II from acting on blood vessel receptors. ARBs have fewer side effects than ACE inhibitors.
  • Calcium channel blockers prevent calcium from acting on blood vessels. These drugs relax (vasodilate) the blood vessels.
  • Beta-blockers decrease the heart rate and also act as vasodilators. Side effects include severe slowing of the heart rate and exacerbation of asthma.
  • Vasodilators work by directly relaxing the walls of the blood vessels.

Generally, high blood pressure is a lifelong condition that requires ongoing treatment after the blood pressure is under control. Because hypertension is asymptomatic, many patients do not properly adhere to their treatment regimens, making the condition difficult to control.


In many cases, hypertension is preventable with lifestyle factors, such as:

  • Maintaining a low-fat and low-sodium diet
  • Adopting a good exercise regimen
  • Maintenance of a normal body weight
  • Smoking cessation
  • Stress management.

In addition, early treatment of patients with prehypertension or hypertension reduces the risk of cardiovascular complications.


  • Victor RG. Chapter 67. Arterial Hypertension. In: Goldman L, Schafer AI, eds. Goldman’s Cecil Medicine, 24e. Philadelphia, PA: Elsevier Saunders; 2012.
  • Hypertension (High Blood Pressure). Cleveland Clinic website. Accessed June 1, 2014.
  • High Blood Pressure Fact Sheet. Centers for Disease Control and Prevention. Accessed June 1, 2014.
  • What is High blood Pressure? National Heart, Lung, and Blood Institute; National Institutes of Health website. Accessed June 1, 2014.

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Tina Shahian, PhD

Tina is a writer for Innerbody Research, where she has written a large body of informative guides about health conditions.


A communication specialist in life science and biotech subjects, Tina’s successful career is rooted in her ability to convey complex scientific topics to diverse audiences. Tina earned her PhD in Biochemistry from the University of California, San Francisco and her BS degree in Cell Biology from U.C. Davis. Tina Shahian’s Linkedin profile.


In her spare time, Tina enjoys drawing science-related cartoons.